Physiologic agents of differentiation will be studied alone and in combination in the study of myeloid and leukemic cell maturation. Monoclonal antibodies specific for myeloid antigens will be utilized along with morphologic and histochemical analysis in order to analyze the fidelity of induced leukemic cell maturation. Studies of antigen modulation by monoclonal antibodies will be performed in order to define mechanisms by which leukemic cells escape lysis. The role of differentiating agents along with combinations of monoclonal antibodies in preventing antigen modulation and selection of resistant cells will be explored. In addition, the ability of differentiated leukemic cells to function as effector cells would be examined. It is hoped that results from these interlock to permit a greater understanding and improved therapy of AML. Clinical studies of the efficacy of differentiating agents and monoclonal antibodies in the treatment of AML are underway at the Dartmouth-Hitchcock Medical Center.